WO2009121365A1

WO2009121365A1 - Microfluidic component capable of self-sealing

Info

Publication number: WO2009121365A1
Application number: PCT/DK2009/000083
Authority: WO
Inventors: Detlef Snakenborg
Original assignee: Danmarks Tekniske Universitet
Priority date: 2008-04-02
Filing date: 2009-04-02
Publication date: 2009-10-08
Also published as: EP2106856A1

Abstract

A microfluidic component (100) for building a microfluidic system is provided. The microfluidic component (100) can be mounted on a microf luidic breadboard (202) in a manner that allows it to be connected to other microfluidic components (204, 206) without the requirement of additional devices. The microfluidic component (100) comprises at least one flexible tube piece (102) for transporting a fluid. The microfluidic component (100) also comprises means for applying and maintaining pressure (104) between the flexible tube piece (102) and a tube piece (208, 210) housed in another microfluidic component (204, 206). Applying the pressure causes the two tubes to be fluidically sealed.

Description

MICROFLUIDIC COMPONENT CAPABLE OF SELF-SEALING

FIELD OF THE INVENTION

This invention, in general, relates to the field of microfluidic technology. In particular, the present invention provides a microfluidic component capable of self sealing for building a microfluidic system.

BACKGROUND OF THE INVENTION

Since the first integrated circuit was invented, miniaturization has become an important research topic in both electronic and non-electronic devices. In the late 1970s, miniaturization was extended to mechanical devices with electronics, which is now known as microelectromechanical systems (MEMS). MEMS research has been largely encouraged by the first introduction of miniaturized total analysis systems and MEMS systems are widely employed in areas from biomedical and drug delivery to space and fuel cell microfluidic systems. These systems have been reduced in size to micro scale for the realization of a fully integrated microfluidic system, such as lab-on-a-chip or a micro total analysis system. Major advantages of miniaturization are the drastic decrease in chemical reaction time and less consumption of expensive chemical reagents, as well as enhancement of reliability. As such fully integrated microfluidic systems are expensive to realize in a chip or analysis system, it is essential that the functionality is as desired. It is therefore required that the systems are thoroughly tested prior to the final miniaturization. Microfluidic systems are therefore well-suited in an experiential setting or in the context of research.

Microfluidic systems are typically built up of a plurality of components, such as microfluidic chips, valves, or components serving as links and delays. The trend of microfluidics goes more and more to hybrid systems since highly integrated devices are difficult to realize due to their complexity. This means that only a limited functionality is integrated in the microchip. Additional functions are realized by conventional or miniaturized external components that are connected to the microfluidic component using tubes.

Fluidic interconnections between miniaturized devices or to external components are still a challenge owing to the small dimensions and the extremely low volume of fluids.

Screw fittings are the most common technique to interconnect tubes and components. The disadvantage of this technique is that very small fittings have to be screwed into components, which is difficult, especially on small components, limiting miniaturization and requiring practical skills and specific tools.

As a tool for developing microfluidic devices the breadboard concept, known from e.g. electronic test circuits, has been adapted. On these microfluidic breadboards the microfluidic components are interconnected, making it possible to test, alter and retest components in a synchronous fluid management environment. However, unlike electronic breadboards, there is no standardization of discrete microfluidic components.

One technique used to interconnect microfluidic components on a microfluidic breadboard includes using a board, which contains microchannels to connect the individual microfluidic components. The disadvantage of systems using this technique is that separate sealing rings or tube packings are needed in order to obtain a leakage free system. Further the limitation of such systems is that they are not compatible with components purchased from third party vendors. Also, the channels in the baseplate induce extra deadvolume and increase the risk of contamination due to the fact that they are exposed to the sample. Another type of breadboard from Labsmith company for example uses small screw fittings in combination with capillaries. However, this setting is not practical due to the above mentioned facts.

The mechanism behind a sealed interconnection is to establish a junction between two openings. Some prior art method use a soft or elastic element acting as a gasket. The purpose of the gasket is to compensate for roughnesses and microscratches at the surface of the sealable elements. A certain mechanical force (stress is simply wrong in this context) applied to the gasket (resulting in a sufficient closing force to counteract the hydraulic pressure inside the system that has to be sealed) is required to ensure a proper sealing. This force can be generated by means of clamping or screwing the two elements, with the gasket in between, together. However, clamping or screwing are not practical for miniaturized systems since they require bulky elements to achieve the required force.

OBJECT AND SUMMARY OF THE INVENTION

The objective of the present invention is to introduce a new type of fluidic interconnection that allows to connect miniaturized components individually as wells as utilized on a breadboard.

In one embodiment the microfluidic component comprises at least one flexible tube piece in a curved state adapted to be mounted next to a second microfluidic component comprising means of conducting a fluid, wherein at least one end of said flexible tube piece is adapted to be sealable connected to an end of said second microfluidic component. Said microfluidic component comprises means for applying and maintaining a pressure to said flexible tube piece so that an end of said flexible tube piece extends towards and presses against an end of the second tube piece in the second microfluidic component. The advantage of this microfluidic component is that sealed connections to other microfluidic components can be obtained on a very small scale. Further no extra parts or devices are needed to make these leakage free connections, and the connections between different microfluidic components can easily be configured and reconfigured. Hereby microfluidic systems can be built without the need for any special skills or tools. Could we skip this section on sealing. We should focus on the fact that we provide a force, I do not believe that we get a patent on pressing elastic material on flexible material... and nobody would as this is not realy an innovative step for a microfluidic system to make connection sealed by pressing rubber onto plastic...

If a straight piece of flexible tube is curved in the middle its projected length decreases. Straightening the tube results in increasing its projected length.

If the tube ends of a curved flexible tube are in a bookended contact with a seal-aiding element, a pressure towards the seal-aiding element is generated when straightening the tube and sealing is established. Aligning both tubes sufficiently allows to establish a sealed fluidic interconnection.

In an embodiment the seal-aiding element is a tube piece made from an elastomeric material. Hereby the tube piece can be easily moved from a connected position to an unconnected position. Further an elastomeric tube piece is well suited for establishing sealed connections between tube pieces.

In another embodiment sealing is ensured by a conical shape male-female mechanism between the ends of the flexible tube and the adjacent component.

Various mechanisms are possible to transform the flexible tube from a curved stage to a state applying and maintaining pressure.towards the second tube. In an embodiment, the means for applying a movement and maintaining a pressure is embodied as a mechanical mechanism. Such mechanical mechanism can be embodied as a lever, a spring, a screw or the like. The advantage of such mechanical mechanisms is that they are very simple to construct and operate, whereby the tube piece of the microfluidic component can be easily moved. The movement that results from this actuation can be a longitudinal movement or a rotational movement (see figure x and x+1). The mechanism that counteracts the reacting force between two adjacent building blocks can be a mechanical interlocking to the above mentioned breadboard or a mechanical interlocking between two adjacent microfluidic components (figure y and figure y+1).

In a further embodiment the means for applying and maintaining a pressure is an electrical mechanism. The advantage of this embodiment is that such means are easy to control, e.g. from a remote position relative to the microfluidic component.

In one embodiment the means for applying and maintaining a pressure is thermally activated. Apart from the advantages listed above, this embodiment can advantageously influence (e.g. temperature control) the fluidic flow in the tube pieces thermally.

In one embodiment the means for applying and maintaining a pressure is pneumatically or hydraulically activated.

In another embodiment the microfluidic component comprises mounting means enabling mounting of said component to a board for connecting said component to other microfluidic components. The advantage of this embodiment is that whole integrated fluidic systems can be configured and reconfigured, serving desired purposes. In a further embodiment the microfluidic component comprises means for directly connecting said component to another microfluidic component. Hereby the above mentioned board can be omitted, without jeopardizing the sealed connection(s) between the microfluidic components.

BRIEF DESCRIPTION OF THE DRAWINGS

Further aspects of the present invention together with additional features contributing thereto and advantages occurring there from will be apparent from the description of preferred embodiments of the present invention which are shown in the accompanying drawing figures, where

figure 1 illustrates the principle of a microfluidic component according to the present invention;

figure 2 illustrates a microfluidic system where a microfluidic component is to be connected according to the present invention;

figure 3 illustrates a microfluidic system where a microfluidic component has been connected according to the present invention;

figure 4 illustrates the principle of a microfluidic component, where the means for maintaining a pressure is a mechanical mechanism comprising a lever;

figure 5 illustrates the principle of a microfluidic component, where the means for maintaining a pressure is a mechanical mechanism comprising a spring;

figure 6 illustrates a microfluidic component where the tube can be adjusted by using a cam;

figure 7 illustrates a microfluidic component comprising two tube pieces arranged at the two sides, where the tube pieces can exit the component; figure 8 illustrates a microfluidic component, comprising two parallel tube pieces, which can be connected to two or four other microfluidic components;

figure 9a-e illustrates a microfluidic component having an angled, a curved, a U-shape, an S-shape and a Y-shape, respectively;

figure 10 illustrates a cross-sectional view of a microfluidic component comprising a number of protrusions for interaction with for example a breadboard comprising a number of indentations, enabling a male/female connection;

figure 11 illustrates a cross-sectional view of a microfluidic component comprising a number of indentations for interaction with for example a breadboard comprising a number of protrusions, enabling a male/female connection;

figures 12 and 13 illustrates respectively a "force movement" on the flexible tube that can be longitudinal or rotational.

DESCRIPTION OF EMBODIMENTS

Figure 1 illustrates a microfludic component 100 in accordance with one embodiment of the invention. The microfludic component 100 comprises a flexible tube piece 102, means for applying and maintaining a pressure 104 and protrusions 106.

The tube piece 102 extends out of sides (not indicated) of the microfluidic component 100. This position of the tube piece 102 is maintained by the means for applying and maintaining a pressure 104. When the means for applying and maintaining a pressure 104 is deactivated (not shown) the tube piece is in a curved state (102) and does not extend out of the microfluidic component 100.

The position of the ends of the flexible tube piece 102 is maintained by guide holes in which the tube is allowed to slide.

The microfludic component 100 can be connected physically to other microfluidic components either directly or on by placing them on a microfluidic breadboard. The latter is enabled placing the protrusions 106 of the microfluidic component 100 in corresponding holes or indentations on a microfluidic breadboard. Arranging the microfludic component 100 on the microfludic breadboard provides the microfludic component 100 with an alignment and a fixation.

The microfluidic components are mounted such that the tube pieces 102 housed in the microfluidic components can interface with each other, and thereby establish a sealed connection between the tube pieces 102 by activating the means for maintaining a pressure 104 of the microfluidic component 100. The tube pieces 102 can be flexible or elastomeric, and be made of e.g. a polymer, teflon or the like. Further the tube pieces 102 can be made of a solvent resistant material such that it transports fluids without any wear and tear.

The tube pieces 102 could also be a fiber optic cable.

In one embodiment of the invention the means for applying and maintaining a pressure 104 is a mechanical mechanism, such as a lever, spring, screw or the like (see figure 4-6 for embodiments). In another embodiment of the invention the means for applying and maintaining a pressure 104 is an electrical mechanism. In yet another embodiment of the invention, the means for applying and maintaining a pressure 104 is activated thermally.

In a further embodiment of the present invention the tube piece 102 of the microfluidic component 100 comprises sealing pads (not shown) or the like at each end of the tube piece 102. Hereby the contact face between the tube piece 102 and tube pieces comprised in other microfluidic components can be larger than the diameter of the tube piece 102 ensuring a better sealed contact between the tube pieces. The pads can also have different geometries, e.g. male/female, suitable in obtaining a sealed contact.

Figure 2 illustrates a microfluidic system (not indicated) comprising a microfluidic breadboard 202 and microfluidic components 100, 204, 206. The microfluidic component 100 is to be mounted on the microfluidic breadboard 202 between the two microfluidic components 204, 206. The microfluidic component 100 comprises a tube piece 102, means for applying and maintaining a pressure 104 and protrusions 106, and has a functionality resembling the one described in figure 1. The microfluidic components 204, 206 comprise tube pieces 208, 210, respectively. By means of protrusions (not shown), the microfluidic components 204, 206 have been mounted on the microfluidic breadboard 202. The means for maintaining a pressure 104 has not been activated, whereas the tube piece 102 does not extend out of the microfluidic component 100. In another embodiment of the invention, the microfluidic components 204, 206 can have a different functionality and dimensions.

Figure 3 illustrates the microfluidic system (not indicated) described in figure 2, where the microfluidic component 100 has been placed between the two microfluidic components 204, 206, on the microfluidic breadboard 202. The means for applying and maintaining pressure 104 has been activated, whereby the ends (not indicated) of the tube piece 102 extends out of the microfluidic components 100. Thus, the tube piece 208 is sealable connected to the tube piece 102, and the tube piece 210 is sealable connected to the tube piece 102. The necessary stress required for making the sealable connections between the tube pieces 102, 208, 210, is realized by the means for applying and maintaining pressure 104. In other words, the impermeable sealing is realized by pressing the ends of the tube pieces 102, 208, 210 against each other.

Figures 4a and 4b illustrate the principle of a microfluidic component of the present invention, where the means for maintaining pressure is a mechanical mechanism comprising a spring and a lever. The microfluidic component comprises a tube piece 102, a lever 416, a bar 418 and a spring 420. The lever 416 is hinged at the side of the microfluidic component. The tube piece 102 has a length that enables it to extend out of the microfluidic component. Furthermore the tube piece 102 is arranged in a curved state between the spring 420 and the bar 418. When the lever 416 is pressed downwards (activated) the bar 418 is also forced downwards leading to a compression of the spring 420. Simultaneously the part of the tube piece 102 arranged between the bar 418 and spring 420 is moved downwards, whereby the ends of the tube piece 102 extends out of the microfluidic component. When the lever 416 has been pressed down (activated), a mechanical mechanism (not shown) ensures that the spring 420 remains in a compressed state and thereby maintains the protrusion of the tube piece 102 from the microfluidic component as depicted in figure 4b. When the lever 416 is pressed downwards (activated) again, a mechanical mechanism ensures that the potential energy of the compressed spring 420 is released. Thereby the part of the tube piece 102 arranged between the bar 418 and the spring 420 is moved upwards, and the tube piece 102, spring 420, bar 418 and lever 416 returns to a position as depicted in figure 4a. By using a lever 416 only a small force is needed to activate the microfluidic component.

Figures 5a-d illustrate the principle of different microfluidic components, where the means for maintaining pressure is a mechanical mechanism comprising a spring and a member or bar. Figure 5a and 5b illustrates a microfluidic component in two different positions or states. The microfluidic component comprises a tube piece in a curved state 102, a spring 420, and a member 522. The length of the tube piece 102 enables it to extend out of the microfluidic component. Furthermore the tube piece 102 is arranged between the spring 420 and the member 522. When the member 522 is pressed downwards the spring 420 is compressed and the part of the tube piece 102 arranged between the spring 420 and the member 522 is moved downwards. As illustrated in figure 5b the member 522 can be moved in a position where a surface part (not indicated) of the member 522 rests against an inner surface (not indicated) of the microfluidic component. Hereby the spring 420 remains in a compressed state and the tube piece 102 maintains its position where the ends extend out of the microfluidic component. When the member 522 is moved out of the position depicted on figure 5b, the potential energy of the spring 420 is released. Hereby the tube piece 102 returns to a position where none of its ends extend out of the microfluidic component as depicted in figure 5a.

Figures 5c and 5d illustrate a microfluidic component in two different positions or states. The microfluidic component comprises a tube piece in a curved state 102, a spring 420, and a bar 524. The tube piece 102 has a length that enables it to extend out of the microfluidic component. Furthermore the tube piece 102 is arranged between the spring 420 and bar 524. The bar 524 can be moved from the bottom side of the microfluidic component. When the microfluidic component is placed on e.g. a microfluidic breadboard (not shown), the bar 524 is pressed upwards and the spring 420 is compressed, whereby the position of the tube piece 102, arranged between the spring 420 and the bar 524, moves upwards relative to the microfluidic component. Hereby the end of the tube piece 102 extends out of the microfluidic component as illustrated in figure 5d. When the microfluidic component is moved from the microfluidic breadboard (not shown) the potential energy of the spring 420 is released and the ends of the tube piece 102 are moved into the microfluidic component as depicted in figure 5c. An advantage with this embodiment compared to the one described using figure 4 is that it allows having a one step process simultaneously maintaining pressure and ensuring integration to a microfluidic breadboard.

Figure 6 illustrates a microfluidic component where the position of the tube piece 102 can be adjusted by using a cam 629. The microfluidic component comprises a tube piece in a curved state 102, a cam 629 and a tube holder 628. The tube piece 102 is arranged in the tube holder 628, vertically moveable inside the microfluidic component. The tube holder 628 comprises a tap 625 positioned in an elongated curved hole 626 of the cam 629. Furthermore the cam 629 is hinged to the microfluidic component and pivotable around the axis 627. When the cam 629 is moved from the position depicted in figure 6a to the position depicted in figure 6b, it causes a vertical movement of the tube holder 628. That is the movement of the tube holder 628 is guided by the cam 629, as the tap 625 is guided from one end (not indicated) of the elongated curved hole 626 to the other end (not indicated). The movement of the cam 629 from the position depicted in figure 6a to the position depicted in figure 6b causes a movement of the tube piece 102 such that its ends extend out of the microfluidic component as depicted in figure 6b.

Figure 7 illustrates a microfluidic component comprising a tube piece 102 arranged such that each end of the tube piece 102 can be moved separately. The microfluidic component comprises a tube piece 102 and two means for maintaining pressure 104. The means for maintaining pressure 104 and the way that the two ends of the tube piece 102 can be moved, correspond to the principles described in figure 1. Hence the microfluidic component deviates from this embodiment by comprising two means for maintaining pressure that can be used to move each end of the tube piece 102 separately. In another embodiment of the invention, the tube piece 102 can only move out of one end of the microfludic component. The means for maintaining pressure 104 can also be embodied as described above.

Figure 8 illustrates an example of a microfluidic component, comprising two parallel tube pieces in a curved state 102, which can be connected to at least two and maximum four other microfluidic components. The tube pieces 102 are depicted in state where they do not extend out of the microfluidic component. By activating means for maintaining pressure (not shown) the ends of the tube pieces 102 can extend out of the microfluidic component. Such means for maintaining pressure (not shown) can be used to move the both tubes pieces 102 or each of them individually. In another embodiment the microfluidic component can comprise four means for maintaining pressure for an individual movement of each of the ends of the two tubes pieces 102.

Figures 9a-e illustrate a tube piece 102 of a microfluidic component having an angled shape, a curved shape, a U-shape, a Z-shape and a Y-shape, respectively. These microfluidic components can be used to connect to other microfluidic components e.g. on one or several microfluidic breadboard. The advantage here is that it allows different dimension of distribution of fluid on the same breadboard or several breadboard.

Figure 10 illustrates a side view of a microfluidic component comprising a number of protrusions 106 for interaction with for example a breadboard comprising a number of indentations 930, enabling a male/female connection.

Figure 11 illustrates a side view of a microfluidic component comprising a number of indentations 932 for interaction with for example a breadboard comprising a number of protrusions 934, enabling a male/female connection.

While this invention has been described in detail with reference to certain preferred embodiments, it should be appreciated that the present invention is not limited to those precise embodiments.

During the description the wording pressure means has been used meaning means providing a "force movement" on the flexible tube that can be longitudinal as illustrated in figure 12 or rotational as illustrated in figure 13, but not limited to these.

The described components could be used e.g. for:

- toys market (part of some toys like "Lego plug-and-play" element to be interconnected to other elements though means of interconnection or on a breadboard

- microfluidic market as a platform with add on elements like breadbord, heather, pump, sensors, valve, microfluidic chips, optical detection cells...built in a way that all elements can be interconnected with the same design or on a breadboard. The microfluidic market comprises using the invention in connection with analytical Life Science, microfluidic research development, diagnostic applications. The components could be sold as single parts or as parts in a kit containing the previous.

REFERENCES

100 microfluidic component

102 tube piece

104 means for applying and maintaining pressure

106 protrusion

202 microfluidic breadboard

204 microfluidic component

206 microfluidic component

208 tube piece

210 tube piece

416 lever

418 bar

420 spring

522 member

524 bar

625 tap

626 elongated curved hole

627 cam axis

628 tube holder

629 cam

930 indentation

932 indentation

934 protrusion

Claims

1. A microfluidic component comprising at least one flexible tube piece in a curved state adapted to be mounted next to a second microfluidic component comprising a canal or at least one second tube piece, wherein at least one end of said flexible tube piece is adapted to be sealable connected to an end of said second canal or tube piece in said second microfluidic component, wherein said microfluidic component comprises means for applying and maintaining a pressure to said flexible tube piece so that an end of said flexible tube piece extends towards and presses against an end of said second tube piece in said second microfluidic component.

2. A microfluidic component according to claim 1 , wherein said flexible tube piece is made from an elastomeric material.

3. A microfluidic component according to claims 1-2, wherein said means of applying a pressure result from a longitudinal movement

4. A microfluidic component according to claims 1-2, wherein said means of applying a pressure result from a rotational movement

5. A microfluidic component according to claims 1-2, wherein said means for applying and maintaining a pressure is a mechanical mechanism.

6. A microfluidic component according to claim 5, wherein said mechanical mechanism is a lever.

7. A microfluidic component according to claim 5, wherein said mechanical mechanism is a spring.

8. A microfluidic component according to claim 5, wherein said mechanical mechanism is a screw.

9. A microfluidic component according to claims 1-2, wherein said means for applying and maintaining a pressure is an electrical mechanism.

10. A microfluidic component according to claims 1-2, wherein said means for applying and maintaining a pressure is thermally activated.

11. A microfluidic component according to claims 1-2, wherein said means for applying and maintaining a pressure is pneumatically or hydraulically activated.

12. A microfluidic component according to claims 1-11, wherein said microfluidic component comprises mounting means enabling mounting of said component to a board for connecting said component to other microfluidic components.

13. A microfluidic component according to claims 1-11 , wherein said microfluidic component comprises means for directly connecting said component to another microfluidic component.

14. A method for creating a sealed connection between at least one flexible tube piece in a curved state in a first microfluidic component and a tube piece in a second microfluidic component, wherein said connection is obtained by applying and maintaining a pressure to said flexible tube piece so that an end of said flexible tube piece extends towards and presses against an end of said second tube piece in said second microfluidic component.